The invention relates to offshore oil production apparatus and in particular to a connector for connecting a tieback conductor to a wellhead.
Offshore oil wells may be drilled from a floating platform and thereafter produced to a later constructed, fixed platform. Such a procedure requires the running of tieback conductors from the platform deck to the wellhead. Tubing is then run, surface production trees installed, and the wells produced in the conventional manner.
One conductor, and possibly other concentric conductors, is run to the wellhead from each platform. The largest or outermost conductor is connected and sealed to the wellhead. Horizontal offset may occur between the wellhead centerline and the corresponding platform well location. Angular misalignment between the wellhead and the guidance system of the conductor often occurs. Although the conductor string runs through guides located on the platform structure at various elevations, offset may occur as a result of inherent manufacturing and installation tolerances. Centralizers may be eccentrically located on the conductor to compensate for this misalignment.
The problem remains, however, of angular misalignment between the conductor and the wellhead as the conductor approaches the wellhead. Existing tieback tools cannot be engaged if the angular misalignment exceeds 0.5 degrees. Attempts to make up the joint may result in damage to the threads.
Seals are provided between the conductor connector and the wellhead. Rotation of the conductor for make up causes rubbing of the seal under compression with potential damage to the seal. Rotation of the string is cumbersome and does not allow the use of eccentric centralizers affixed to the conductor.